package com.self.ry.utils;


import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.InputStream;

/**
 * CRC校验工具类
 *
 */
public class CRCUtil {
    static int crc_ccitt_table[] =
            {
                    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
                    0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
                    0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
                    0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
                    0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
                    0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
                    0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
                    0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
                    0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
                    0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
                    0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
                    0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
                    0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
                    0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
                    0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
                    0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
                    0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
                    0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
                    0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
                    0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
                    0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
                    0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
                    0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
                    0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
                    0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
                    0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
                    0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
                    0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
                    0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
                    0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
                    0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
                    0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
            };


    public static int CRC_CCITT_16(int CRC, byte[] data, int data_length) {
        int da = 0;
        int ii = 0;
        int crchl = 0;
        int idx = 0;
        crchl = CRC;
        for (ii = 0x00; ii < data_length; ii++) {
            da = (crchl / 256);
            crchl <<= 0x08;
            crchl = crchl & 0x0FFFF;
            idx = da ^ data[ii];
            idx = idx & 0x0FF;
            crchl ^= crc_ccitt_table[idx];
            crchl = crchl & 0x0FFFF;
        }
        return crchl & 0x0FFFF;
    }

    public static int CRC_MSG_16(int CRC, byte[] data, int startpos, int data_length) {
        int da = 0;
        int ii = 0;
        int crchl = 0;
        int idx = 0;
        crchl = CRC;
        for (ii = 0x00; ii < data_length + startpos; ii++) {
            if (ii < startpos) continue;
            da = (crchl / 256);
            crchl <<= 0x08;
            crchl = crchl & 0x0FFFF;
            idx = da ^ data[ii];
            idx = idx & 0x0FF;
            crchl ^= crc_ccitt_table[idx];
            crchl = crchl & 0x0FFFF;
        }
        return crchl & 0x0FFFF;
    }

    public static int CRC_CCITT_16_2(byte[] data1, int length1, byte[] data2, int length2) {
        int CRC1 = CRC_CCITT_16(0, data1, length1);
        int CRC2 = CRC_CCITT_16(CRC1, data2, length2);
        return CRC2;
    }

    public static int CRCFromFile(String filePath) {
        int CRC = 0;
        try (DataInputStream dataIn = new DataInputStream(new BufferedInputStream(new FileInputStream(filePath)))) {
            byte[] buf = new byte[4096];
            while (true) {
                int len = dataIn.read(buf);
                if (len < 0)
                    break;

                CRC = CRC_CCITT_16(CRC, buf, len);
            }
        } catch (Exception e) {
            e.printStackTrace();
            return CRC;
        }

        return CRC;
    }


    public static int FileSize(String filePath) {
        int fileSize = 0;
        try (InputStream in = new FileInputStream(filePath)) {
            fileSize = in.available();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return fileSize;
    }

    /**
     * 最后一位的校验位
     *
     * @param order
     * @return
     */
    public static String checkSum(String order) {
        String[] orderArray = order.split(" ");
        int i = 0;
        for (String s : orderArray) {
            i = i + Integer.parseInt(s, 16);
        }
        i = i & 0xff;
        String s = Integer.toHexString(i);
        if (s.length() == 1) {
            s = "0" + s;
        }
        return s;
    }
}

